Fragment re-created on bottom navigation view item selected

Question

Following is my code for bottom navigation view item selected

bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationI         


        

Answer 1

Be careful when using replace. Even if providing a fragment that already exists in memory, replace will restart the fragment's lifecycle. To avoid a restart, the transaction object's methods includes add, show, and hide, which can be used to show the correct fragment without restarting it.

private fun switchFragment(selectedTabIndex: Int) {
    val previousTabIndex = this.currentTabIndex
    this.currentTabIndex = selectedTabIndex

    val transaction = supportFragmentManager.beginTransaction()
    val tag = fragments[this.currentTabIndex].tag

    // if the fragment has not yet been added to the container, add it first
    if (supportFragmentManager.findFragmentByTag(tag) == null) {
        transaction.add(R.id.container, fragments[this.currentTabIndex], tag)
    }

    transaction.hide(fragments[previousTabIndex])
    transaction.show(fragments[this.currentTabIndex])
    transaction.commit()
}